Friction spring



Dec. 5,1933. E, LE 1,938,099

FRICTION SPRING Filed May 17, 1932 I dlbgaENTol cat/91 Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE FRICTION SPRING Louis E. Endsley, Pittsburgh, Pa. Application May 17, 1932. Serial No. 611,763 2 Claims. (Cl. 267-1) My invention relates to friction springs for Only so much of the structure is shown as is draft gears, or carrying springs for freight cars, necessary to an understanding of my invention.

of the type wherein two coils are arranged in sub- It will be understood that the coils may be placed stantially concentric relation and have cooperatwithin a casing or housing of any well-known v ing frictional camming surfaces, whereby when type, with suitable seating blocks for the ends of 60 the one coil is compressed in the direction of its the springs. axis, the other coil will be compressed longitudi- The inner or load-carrying coil is represented nally and expanded radially. by the numeral 5 and the outer or friction coil Heretofore it has been common practice to so by the numeral 6- The Wid h of the Ou e tu n arrange the springs that the load-carrying coil a d cated by e a w is greater than t 65 will be fully compressed before the turns of the gr a es xial dimension of th inner turnsfriction coil are fully compressed, or to cause the For xamp e, e dimension at 7 y be turns of both coils to be simultaneously cominch, While t Width of e inner 0 as dipressed. cated at 8, may be .78 inch. These dimensions In these older types of friction springs, the iny, of u e, b v it being desirable ner coil is the principal load-carrying coil. In v o ve th Outer'tllrns of greater Width other words, it is subjected to greater stresses than the inner turns. The outer turns have and more severe distortion than the outer coil, e r abut su ac 9 w d d i adial d ecparticularly on lighter impacts or-impacts which tiens to p v d a Wide contacting area When e do not fully compress the springs. The result is Outer Coils e c p that the inner spring is very short-lived compared The inclined or camming surfaces 10 and 11 on to the outer coil and requires frequent renewal. the 0011s 5 a r p v result in'radial X- One object of my invention is to provide a pension of the Outer coil When h inner Spring structure wherein the stresses, and particularly s compressed. d a the turns o e Outer 0011 those which do not fully compress the coils, are are successively brought i to abutting or solid distributed more evenly to the coils, with consem nt wi h on n h r, he turns of the quent increase in life of the springs, a d fewer inner coil are successively compressed. When the repairs or replacements, surfaces 9 of the outer coil are brought into abut- 30 Another object of my invention is to provide a ting engagement, friction is developed 011 uc spring structure of such form th t impacts of surfaces 9 through the radial and rotative movegreater force are required to move the inner ments of the u s 0f the 0011 and particularly spring solid than in previous structures of simiin the d u ns the eo lar size or weight. It will be seen that by reason of the greater 35 Another object of my invention is to provide width of the outer p i u s, th y wi l be a spring structure wherein the width of each brought into solid or abutting engagement in adturn of the outer coil is greater in directions axi- Vance 0f the inner turns, W e re ult that ally of the coil than the width of the inner turns, the inner pr i relieved of a p ti n f the whereby the turns of theouter coil are brought compression Strains Which Would be imp s d successively intoabutting engagement in adthereon if the turns of the inner spring w r comva e of the dj t tur of th inner L pressed into contact with one another in advance Another object of my invention is to provide 0f the turns of the Outer sp in or if the said radially-extending frictional contacting surfaces inner turns Were fully Compressed l o sly on the abutting surfaces of the outer turns. With the Complete Compression 0f the Outer pr Another object of my invention is to provide Compressing 0f the inner p g a so results in a spring structure wherein the end turns of the radial expansion of the Outer p h resultouter coil have a greater range of sli to proant rotative movement of some of the outer turns, duce increased friction against the turns of the particularlynear the ends of the outer spring. inner coil and the end seats of the spring than in These end turns, of course, seat against blocks or older types of draft gears. other surfaces.

5 One form which my invention may take is Although the thrust or compression forces are shown in the accompanying drawing wherein less between the surfaces 10 and 11 in the end Figure 1 is a longitudinal sectional view of the turns of the coils than at the middle turns, the spring structure in expanded condition; Fig. 2 is end turns have greater rotative movement, and

55 a similar view showing the coils compressed. and the friction on the surfaces 9, 10 and 11 is thereby Fig. 3 is an end view of the structure. increased. These friction surfaces not only incoils, the axially-extending width of the turns in the friction coil being greater than the width of the turns of the load-carrying coil.

2. Friction spring structure comprising normally-expanded concentric coils having cooperating frictional surfaces inclined with respect to the axis of the coils, the axially-extending width 01 the turns in the outer coil being greater than the width of the inner turns, and the edges of the outer turns being flattened to provide wide contacting surfaces between said outer turns.

LOUIS E. ENDSLEY. 

